The era of Big Data has only just begun. Big data is an emerging paradigm application to datasets whose size or complexity is beyond the ability of commonly used computer software and hardware tools. Big Data creates a radical shift in how we think about research. “Big data…… has become prevalent in our lives” (Betsy Burton, Gartner Analyst). Big data becomes very important driver for innovation and growth. The focus of present paper is to provide a summary existing literature to know about the background of big data along with its challenges and applications. This paper also elaborates the ‘HACE Theorem’ that states the characteristics of the Big Data revolution.